drm/amdgpu: add drm-client-id to fdinfo v2

This is enough to get gputop working :)

v2: rebase and some addition cleanup

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Shashank Sharma <shashank.sharma@amd.com> (v1)
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>